Pharmaceutical samples spectrometry

Gaudry and Ploux (180) summarized recent HPLC, TLC, GC, column chromatography, paper chromatography, and LC-mass spectrometry techniques for biotin in biological and pharmaceutical samples. Russell (44) reviewed a recent HPLC determination for biotin in royal jelly. 

Liquid chromatography/mass spectrometry (LC/MS)-based techniques provide unique capabilities for pharmaceutical analysis. LC/MS methods are applicable to a wide range of compounds of pharmaceutical interest, and they feature powerful analytical figures of merit (sensitivity, selectivity, speed of analysis, and cost-effectiveness). These analytical features have continually improved, resulting in easier-to-use and more reliable instruments. These developments coincided with the pharmaceutical industry s focus on describing the collective properties of novel compounds in a rapid, precise, and quantitative way. As a result, the predominant pharmaceutical sample type shifted from nontrace/pure samples to trace mixtures (i.e., protein digests, natural products, automated synthesis, bile, plasma, urine). The results of these developments have been sig-... 

Williams, J.P. and Scrivens J.H., Rapid and accurate mass desorption electrospray ionization tandem mass spectrometry of pharmaceutical samples, Rapid Commun. Mass Spectrom., 19, 3643, 2005. 

Chen, H. et al., Desorption electrospray ionization mass spectrometry for high-throughput analysis of pharmaceutical samples in the ambient environment, Anal. Chem., 77(21), 6915, 2005. 

In this chapter the topic is the techniques for preparing pharmaceutical samples for analysis. Sample preparation of pharmaceutical products as well as biological samples is discussed. The scope of this chapter includes only sample preparation for chromatographic analysis in which the chromatographic system, not the sample preparation, achieves the ultimate isolation of the analyte. Isolation and purification of relatively pure substances for spectral analysis, e.g., infrared spectroscopy, nuclear magnetic resonance, and mass spectrometry, will be discussed elsewhere. This chapter is organized into three groups of discussions. 

Atomic spectrometry is widely used in many laboratories, particularly whenever trace element analyses are required. Environmental samples are analyzed for heavy-metal contamination, and pharmaceutical samples may be analyzed for metal impurities. The steel industry needs to determine minor components, as well as major ones. The particular technique used wiU depend on the sensitivity required, the number of samples to be analyzed, and whether single-element or multielement measurements are needed. The following discussion gives the capabilities of the techniques. 

Traditional applications for ion mobility spectrometry (IMS) have primarily revolved around security and safety because of the rapid response time of the instrument coupled with its selectivity and sensitivity. Its speed, sensitivity, and selectivity, however, open opportunities for expansion into other areas of analysis. Pharmaceuticals offer a particularly promising target area for application of IMS because, unlike environmental and biological samples, pharmaceutical mixtures are usually well defined and not too complex. In addition, many pharmaceuticals have basic sites on the molecules that produce high proton affinities thus, they respond well to the ion-molecule ionization sources used in positive-mode IMS. Analytical methods currently used in the pharmaceutical industry revolve around some type of chromatography, either liquid or gas, that is usually slow and expensive. For routine, repetitive, and rapid analyses of pharmaceutical samples, IMS offers a unique and efficient alternative to chromatography. 

Quantitative mass spectrometry, also used for pharmaceutical appHcations, involves the use of isotopicaHy labeled internal standards for method calibration and the calculation of percent recoveries (9). Maximum sensitivity is obtained when the mass spectrometer is set to monitor only a few ions, which are characteristic of the target compounds to be quantified, a procedure known as the selected ion monitoring mode (sim). When chlorinated species are to be detected, then two ions from the isotopic envelope can be monitored, and confirmation of the target compound can be based not only on the gc retention time and the mass, but on the ratio of the two ion abundances being close to the theoretically expected value. The spectrometer cycles through the ions in the shortest possible time. This avoids compromising the chromatographic resolution of the gc, because even after extraction the sample contains many compounds in addition to the analyte. To increase sensitivity, some methods use sample concentration techniques. 

Jelic A, Petrovic M, Barcelo D (2009) Multi-residue method for trace level determination of pharmaceuticals in solid samples using pressurized liquid extraction followed by liquid chromatography/quadrupole-linear ion trap mass spectrometry. Talanta 80 363-371... 

The use of direct UV spectrophotometry to measure sample concentrations in pharmaceutical research is uncommon, presumably due to the prevalence and attractiveness of high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) methods. Consequently, most researchers are unfamiliar with the value of UV detection, mainly that it is generally much faster than other methods - a very important asset in high-throughput screening. 

Petrovic M, Hernando MD, Diaz-Cruz MS, Barcelo D (2005) Liquid chromatography-tandem mass spectrometry for the analysis of pharmaceutical residues in environmental samples a review. J Chromatogr A 1067 1-14... 

Modern spectroscopy plays an important role in pharmaceutical analysis. Historically, spectroscopic techniques such as infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS) were used primarily for characterization of drug substances and structure elucidation of synthetic impurities and degradation products. Because of the limitation in specificity (spectral and chemical interference) and sensitivity, spectroscopy alone has assumed a much less important role than chromatographic techniques in quantitative analytical applications. However, spectroscopy offers the significant advantages of simple sample preparation and expeditious operation. 

Atomic techniques such as atomic absorption spectrometry (AA), inductively coupled plasma-optical emission spectrometry (ICP-OES), and inductively coupled plasma-mass spectrometry (ICP-MS), have been widely used in the pharmaceutical industry for metal analysis.190-192 A content uniformity analysis of a calcium salt API tablet formulation by ICP-AES exhibited significantly improved efficiency and fast analysis time (1 min per sample) compared to an HPLC method.193... 

The progress made in interfacingHPLC instruments with mass spectrometry has been a significant development for laboratory analyses in the pharmaceutical industry. The low concentrations of test drugs in extracts of blood, plasmas, serums, and urine are no problem for this highly sensitive HPLC detector. In addition, the analysis is extremely fast. Lots of samples with very low concentrations of the test drugs can thus be analyzed in a very short time. At the MDS Pharma Services facility in Lincoln, Nebraska, for example, a very busy pharmaceutical laboratory houses over 20 LC-MS units, and they are all in heavy use daily. 

Hyphenated analytical techniques such as LC-MS, which combines liquid chromatography and mass spectrometry, are well-developed laboratory tools that are widely used in the pharmaceutical industry. Eor some compounds, mass spectrometry alone is insufficient for complete structural elucidation of unknown compounds nuclear magnetic resonance spectroscopy (NMR) can help elucidate the structure of these compounds (see Chapter 20). Traditionally, NMR experiments are performed on more or less pure samples, in which the signals of a single component dominate. Therefore, the structural analysis of individual components of complex mixtures is normally time-consuming and less cost-effective. The... 

Molecular spectroscopic techniques have been widely used in pharmaceutical analysis for both qualitative (identification of chemical species) and quantitative purposes (determination of concentration of species in pharmaceutical preparations). In many cases, they constitute effective alternatives to chromatographic techniques as they provide results of comparable quality in a more simple and expeditious manner. The differential sensitivity and selectivity of spectroscopic techniques have so far dictated their specihc uses. While UV-vis spectroscopy has typically been used for quantitative analysis by virtue of its high sensitivity, infrared (IR) spectrometry has been employed mainly for the identihcation of chemical compounds on account of its high selectivity. The development and consolidation of spectroscopic techniques have been strongly influenced by additional factors such as the ease of sample preparation and the reproducibility of measurements, which have often dictated their use in quality control analyses of both raw materials and finished products. 

Miao X. and C.D. Metcalfe (2003). Determination of pharmaceuticals in aqueous samples using positive and negative voltage switching microhore liquid chromatography/electrospray ionization tandem mass spectrometry. Journal of Mass Spectrometry 38 27-34. 

Schoenmakers et al. [72] analyzed two representative commercial rubbers by gas chromatography-mass spectrometry (GC-MS) and detected more than 100 different compounds. The rubbers, mixtures of isobutylene and isoprene, were analyzed after being cryogenically grinded and submitted to two different extraction procedures a Sohxlet extraction with a series of solvents and a static-headspace extraction, which entailed placing the sample in a 20-mL sealed vial in an oven at 110°C for 5,20, or 50 min. Although these are not the conditions to which pharmaceutical products are submitted, the results may give an idea of which compounds could be expected from these materials. Residual monomers, isobutylene in the dimeric or tetrameric form, and compounds derived from the scission of the polymeric chain were found in the extracts. Table 32 presents an overview of the nature of the compounds identified in the headspace and Soxhlet extracts of the polymers. While the liquid-phase extraction was able to extract less volatile compounds, the headspace technique was able to show the presence of compounds with low molecular mass... 

The availability of commercial bench-top mass spectrometry detectors for HPLC is facilitating the development of HPLC-MS methods for many analytes. This is more common in pharmaceutical than food applications. As is generally the case, mass spectrometry is first being applied to standard solutions and relatively simple samples before being applied to more complex food matrices. A standard mixture of ten vitamers, AA, DHAA, PN, PL, PM, thiamine, nicotinic acid, nicotinamide, pantothenic acid and biotin, were recently determined by HPLC-particle beam... 

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